[Python-checkins] r76228 - python/branches/release31-maint/Doc/whatsnew/3.1.rst

[raymond.hettinger]

Author: raymond.hettinger
Date: Thu Nov 12 18:42:47 2009
New Revision: 76228

Log:
Add examples to whatsnew entry for OrderedDict.

Modified:
   python/branches/release31-maint/Doc/whatsnew/3.1.rst

Modified: python/branches/release31-maint/Doc/whatsnew/3.1.rst
==============================================================================
--- python/branches/release31-maint/Doc/whatsnew/3.1.rst	(original)
+++ python/branches/release31-maint/Doc/whatsnew/3.1.rst	Thu Nov 12 18:42:47 2009
@@ -81,6 +81,28 @@
       PEP written by Armin Ronacher and Raymond Hettinger.  Implementation
       written by Raymond Hettinger.
 
+Since an ordered dictionary remembers its insertion order, it can be used
+in conjuction with sorting to make a sorted dictionary::
+
+    >>> # regular unsorted dictionary
+    >>> d = {'banana': 3, 'apple':4, 'pear': 1, 'orange': 2}
+
+    >>> # dictionary sorted by key
+    >>> OrderedDict(sorted(d.items(), key=lambda t: t[0]))
+    OrderedDict([('apple', 4), ('banana', 3), ('orange', 2), ('pear', 1)])
+
+    >>> # dictionary sorted by value
+    >>> OrderedDict(sorted(d.items(), key=lambda t: t[1]))
+    OrderedDict([('pear', 1), ('orange', 2), ('banana', 3), ('apple', 4)])
+
+    >>> # dictionary sorted by length of the key string
+    >>> OrderedDict(sorted(d.items(), key=lambda t: len(t[0])))
+    OrderedDict([('pear', 1), ('apple', 4), ('orange', 2), ('banana', 3)])
+
+The new sorted dictionaries maintain their sort order when entries
+are deleted.  But when new keys are added, the keys are appended
+to the end and the sort is not maintained.
+
 
 PEP 378: Format Specifier for Thousands Separator
 =================================================